Our recent studies have shown that the intracellular phases in the synthetic cycle of mucus-secreting cells in human airways are distinct and dissociated events. The objective of this study is to establish the pattern of control of each phase, i.e. precursor uptake, glycoprotein synthesis and discharge. In particular, analyses will be made of (1) the role of calcium ions, (2) the role of intracellular actomyosin systems, and (3) the modification made to each phase by anti-inflammatory agents. By addition of labelled glycoprotein precursors to human bronchial tissue in organ culture, within four hours, the synthesis and discharge of labelled glycoproteins can be followed by autoradiography. Quantitative microscopic analysis of autoradiographs is used to measure the rates of precursor incorporation, intracellular transport and discharge of glycoproteins. In this way, the variety of mucus-secreting cell types in the bronchial mucosa - mucous and serous cells of the submucosal glands and goblet cells in the surface epithelium - are separately analyzed and compared. Biochemical analysis of mucus glycoproteins secreted into the culture medium enables the extracellular secretion to be related to the intracellular secretory events. In addition, chemical analyses of secreted mucus can be related to the variety of neutral and acid glycoproteins which can be identified within the secretory cell population by histochemical techniques. Mucus secretion is a function of the normal bronchial tree and its hypersecretion a feature of several important respiratory diseases. Since hypersecretion is reflected in bronchial gland hypertrophy, and since this can be assessed in the tissue, the behavior of normal and hypersecreting airways can be compared.